The domestication of pigs occurred independently in two regions, in eastern Anatolia (modern Turkey) and in central China. Analysis of mitochondrial DNA (DNA in the cell that is inherited from the mother) shows that early herders took pigs with them from Anatolia to western Europe where they interbred with wild boar. However, in China, there is little evidence that the domestic herds interbred with wild boars. But early agriculturists took their pigs to southeastern Asia and here they interbred with wild stocks so that all New Guinea domestic pigs and those of the islands in the tropical Pacific Ocean carry DNA from those southeast Asian wild boar populations. The interesting question is why the pigs in central China didn't interbreed with wild boar populations in central China. Dobney suggests that management practices may have made a difference. It is possible that in China where settlements were dense, people started keeping pigs in pens, whereas in Europe, even in medieval times, people took their pigs to forage in the forests, where they might encounter wild boars.

[For full details see: "The Modern View of Domestication," a special issue of PNAS edited by Greger Larson and Dolores R. Piperno]